Electrolytic separation of metal.



mimisrms PATE -OFFICE.

- EDWIN vLcHANcnbF PHILADELPHIA, AND El'JEANDR. KENT, or L NsDowNE,

I r1 PENNSYLVANIA.

- Y mas-mm To. my (Bonded J Betknown that1we,ll nw1N M. CHANGE,

residingatjNo. 4,429 Chestnut street, in. the cltyof Philadelphia, count of Philadelphia, and State of lennsy Vania, and ELnA on Kn 'r, residing at No. i5 Falrview avenue, Lansdownjz, ,in' the county of Dela ware and State ofPe'nnsylva'nia,have'jointly invented a new and useful Process for the Electrolytic Separation of Metal, whereof ,the following isa specification.

Our invention is 'iri marily intended for the winning of metals from mattes or spelsses, although it is adapted to the separation, of metals from various alloys, or other compounds.

The process is based upon our discovery that 'vvhen afmatte, speiss,"or other metallic compound, in a ffused condition, is made the anode of, an electrical circuit, in conjunction with a fused electrolyte ofpr'oper character,

l electrolysis' may be sofcbnducted as to select one or more of themetallic components of the anode and dcposit it or them at the cathode, which latter maybe either a solid, ormay be itself in a fused condition. The

fused electrolyte must'be of such character flth'atit's anion h as, a'iiinity for the metallic some circumstances, may beione whose anion ,alsohas affinity for other of said-inet'alhc component, Qiztzoriiponent, whose separation from the fused,- anode is sought, and, under componentsthan the one or ones whose separation and deposit are desired. In the latter case the electrical conditions must be'so con- I trolled as to permit selectiv 5 action, whereby only .that metal, or-t-hose metals, whose recovery'is des red shall undergo electrolytic deposition toanysubstantial extent.

Inorder to more fully explain the ration ale of 'our'invetition, we'will first describe a typical processl in'which the anion of the fused electrolyte has substantial aflinity for only oneyof themetallic components of the fused anode. In'this instance the compound to be treated may consist of an alloy of lead and silver, and the electrolysis,by means of which the pure lead is recovered at the cathode, may incidentally tend to purify the silver residuum in the anode, though this last mentioned feature is not the direct purpose of the process. An, alloy oflcad and silver, say containing from 2 to 5 percent. of silver, is maintained in afufsed condition and the fused elecsErAnArI'oN or METAL.

fact that the heat 0 trolyte is superimposed upon the surface thereof. This-electrolyte is one whose anion has an oxidizing action, such as the double silicate of lead and sodium. An electrode of proper character, such as" carbon, iron or other substance inert under the conditions of use, is submerged in the fused metallic compound, so that the entire upper surface of the latter, which is in contact with the electrolyte, becomes the anode. The cathode, .(in this instance preferably of carbon or iron) is immersed ill the electrolyte in roper isolation .from the anode surface and t e circuit is then established. Since the anion of the fused electrolyte has, under the conditions mentioned, substantially no affinity for the silver, selective electrolysis ofthe lead ingredient will occur, and the current density and E. M. IF. may be as high as convenience dictates, since the crowding of the cur rent will not interfere with the selective action, which is here due to the practically preponderant ailinity of the anion of the electrolyte for one of the metals. The process may be continued until substantially all of the lead has been recovered. Where, however, the anion of the electrolyte has substantial affinity for more than one metallic con'iponent of the fused anode, it is necessary, in order to insure selective deposition that the cur"ent conditions shall be controlled. As a typical instance of such process, we state the following: The compound to be treated is a copper-iron matte, containing copper 49.8 percent, iron 22.3 percent,

sulfur 23.3 percent, the-remaining constituents being negligible, and 1t is desired to win the copper by electro-deposition at the cathode. In this instance, the fused electrolyte may consist of an alkaline silicate, such for instance, as sodium and potassium meta-silicate, which may with advantage contain about 2% of manganese sesquiox'id, to increase fluidity. While the anion of this electrolyte will form a compound with, both the iron and the .cop er, it is a well-known f formation of the respective compounds is markedly different, that of the iron being substantiall higher than that of the copper. "Under t ese cir-' cumstai'iccs, we have discovered that notwithstanding the aflinity of the anion of the electrolyte for each of the metalliccorgpm nents, the electrolysis may be so controll as to only Patente Feb. 8', 1910.

deposit thatfinetal whose compound ill) ' tially no decomposition whatever occurs as to that ingredient. the heat of formation of whose compound is markedly greater.

Whether this theory be the correct one or not, we have found in practice that the rcquired selective action does take place, for instance, with the copper-iron compound we have just described, under the following vconditions: A source of current having an 16. hi. F. of two volts was employed, the

external resistance being 1.8 olnns, the cur rent flow ng being .14 amperes, the temperature of the fused anode being from 1000 to 1200 degrees centigrade, the distance between the anode and cathode being 6 millimeters, the area of the fused anode surface being 4 square centimeters, and the cathode being an iron rod of 5 millimeters in diame ter, immersed in the electrolyte to a depth of 1 centimeter.

Broadly speal'ring, the two types of our process are identical in those'particulars which are of the essence of the invention, viz.: theemployment of a fused anode and a fused electrolyte, and the variation be tween them may be' said to consist in the fact that the first mentionedtype 'depends substantially upon selective avidityof attack uponthe anode, while the second depends substantially upon the relative. re-

luctance of decomposition of the compo- 45.

nents formed by the attack.

Having given the foregoing typical illus-- trations of our process,- we point out the fact that it is'not to be restricted to the winning or separation of any one metal or group of metals, and that, furthermore, a

. great varietyof electrolytes are available for use in the process. It is obviously impossible in this specification to designate by name, all the metals and allithe electrolytes which lend themselves to our process,

but we can comprehensively state the following rules for its conduct, viz;: that both -ano.de"'and electrolyte shall be in a fused condition, as distinguished from aqueous or other solution; that the anlon of the electrolyte shall have substantial affinity for atv fleast that component of the fused anode whose clectro-deposition at the cathode is sought; illtlt lf the anion of the electrolyte has substantial atiinity for more than one process is conducted.

of the metallic components of the fused cathode, the process can only be selectively employed for the deposition at the cathode,

of the metallic component, or comp0nents,

the heat. of re-action otlwhose compound, or compounds, with the electrolyte an1on, is substantially less than that ot-other conr ponent, or components, whose deposition not'then desired; and that in this atter case,

the difference of potential'aeross the cell nmsl be so controlled as not to afford the energy necessary for the decomposition -of the anion compound, whose metallic componeut has the higher heat. of formation wvitlr the anion. and for the deposition of said metallic component. This latter condition may be ascertained tentatively in any particular instance by an initial test, and the requisite electrical conditions thus determined may be maintained for commercial practice.

Having thus described our invention, we desire to state, that we are, of course, aware of the fact that electrolysis of mattes and speisses has been attempted inthewet way,

the matte or speiss in a solid condition being i,

made the anode of the circuit. But apart xfrom other distinctive characteristics of our process as compared with such processes, a fundamental difference of great ractical importance lies in the fact that t e fused condition of the anode permits the continuous and successive presentation of all portions of the desired metal to the action of the electrolyte, whereas when a solid. matte or speiss is used as the anode the action can only proceed by honey-combing the mass,

with the result of great loss of efficiency, owing to'the local distribution of the metal to be attacked, and its remoteness from the region of greatest advantage, 2'. 6., the plane of contact between the fused electrolyte and the fused anode itself. mental difference of great practical importance lies in the fact that in humid electrolysis, many impurities, such as arsenic, antimony, and sulfur, are diffused through the electrolyte and cause contamination of the cathode itself, while in our process such impurities at once disappear by volatilizetion, owing to the temperature at which the We are also aware that the electrolysis of fused salts for the production and recovery of one or more of the metallic constituents of such salts has been practiced by A further fundas ess above set forth is not. intended to include either the robbing of an electrolyte for the production of metal, or the direct electrolysis of fused metalliferous compounds, but on the contrary is limited to electrolytic separation and recovery, selectively effected from a fused anode, by means of a flifed electrolyte acting in an intermediate ca acity, as a carrier.

We claim,

1. The hereinbefore described improvement in electrolytic separation of metal, which consists in subjecting to the passage of an electric current, a fused metalliferous anode, and a fused electrolyte Whose anlon has selective affinity for a metallic component or components of the anode; and depositing the selective metallic component or components at the cathode, substantially as set forth. I

2. The hereinbefore. described improvement in electrolytic separation of metal,

which consistsin subjecting to the passage of an electric current, a fused metalliferous anode, and a fused electrolyte 'Whose anion has aflinity for metallic components of the anode and tends to form therewith co1rpounds having markedly difierent heats of formation; controlling the difference of potential across the cell to effect selective decomposition of metal; depositing at the cathode the metal, or metals, the heat of formation ofWhose anion compounds is relatively low; the metal, or metals, the heat of formation of Whose anion compounds is relatively high, substantially as set forth.

In testimony whereof, We have hereunto si ned our names, at Philadelphia,

Penn-' and retaining in the electrolyte I sy vania, this thirteenth day of April 1908.

EDWIN M. CHANCE. ELEANQR KENT.

Witnesses:

VERNON B. MILLER, James H. BELL. 

